The present disclosure relates to a device structure of carbon fibers and a manufacturing method thereof.
Carbon nanotubes (CNT) are excellent in terms of electric conductivity, thermal conductivity and a mechanical characteristic and therefore take trial applications to a variety of fields. Hence, an expectation is that the carbon nanotubes will be applied to an electronic device, a heat radiation device, wiring for an LSI (Large Scale Integration), a channel of a transistor, a heat radiation bump and an electron emission source. It is also expected that especially the carbon nanotubes grown in vertical alignment will be applied to the wiring and the heat radiation. Note that a mainstream method of attaining the vertically-aligned growth of the carbon nanotubes is a chemical vapor deposition (CVD) method at the present, and it is generally practiced that the carbon nanotubes (CNT) are grown directly on a desired substrate. The method of attaining the vertically-aligned growth of the carbon nanotubes is exemplified such as a thermal CVD method, a plasma CVD method and a hot filament CVD method. Further, a thermal decomposition method of SiC is exemplified as a method of acquiring the carbon nanotubes close to closest packing.
In the application to the carbon nanotubes, the carbon nanotubes grown in vertical alignment on the substrate are utilized in many cases. Applied examples of the carbon nanotubes are, e.g., the wiring for the LSI and the heat radiation bumps. In the case of applying the carbon nanotubes, it is desirable that the carbon nanotubes having the highest possible density be grown on the substrate in terms of reducing a wiring resistance and improving heat radiation efficiency. The carbon nanotubes grown in vertical alignment by the conventional technique have, however, a low density. Further, some segments of the neighboring carbon nanotubes abut on each other, however, all of the carbon nanotubes are not necessarily brought into contact with each other. Namely, a problem is that an interval between the neighboring carbon nanotubes is expanded. The growth of the carbon nanotubes having the high density is not generally easy, and a volume occupancy rate of the carbon nanotubes grown in vertical alignment by the conventional technique is on the order of 10%. Further, in the thermal decomposition method of SiC, a thermal treatment temperature is 1200° C.-2200° C. It is therefore difficult to select the substrate and make process matching with other devices.